Dynamic equivalent circuit of combined heat and power system, and working method thereof

ABSTRACT

The present disclosure discloses a dynamic equivalent circuit of a combined heat and power system, and a working method thereof. Controlled sources are used to represent a thermoelectric coupling source; equivalent inductance is used to represent a delay of a heat transmission pipeline; equivalent resistance is used to represent a heat load and a heat loss of the heat transmission pipeline; and equivalent capacitance is used to represent a heat storage water tank. A circuit model is used to uniformly represent two thermoelectric heterogeneous energy sources, and a single power simulation tool may be used to simulate a combined heat and power system, so that the simulation system has a simple structure and is easy to develop and maintain.

CROSS REFERENCE TO RELATED APPLICATION(S)

This patent application claims the benefit and priority of ChinesePatent Application No. 202110448868.8, filed on Apr. 25, 2021, thedisclosure of which is incorporated by reference herein in its entiretyas part of the present application.

TECHNICAL FIELD

The present disclosure relates to the field of a combined heat and powersimulation technology, and particularly relates to a dynamic equivalentcircuit of a combined heat and power system, and a working methodthereof.

BACKGROUND ART

The statements in this section merely mention the background art relatedto the present disclosure, and do not necessarily constitute the priorart.

The combined heat and power system has attracted wide attention fromgovernments and enterprises all over the world for its advantages suchas high primary energy utilization efficiency and safe and reliableenergy supply. Electric heating belongs to a heterogeneous energysource, its physical characteristics and disciplines are very different,and representation manners and research methods are not unified. Anexisting simulation system uses multiple types of energy simulationsoftware to co-simulate multi-energy systems, such as a combined heatand power system, by means of data communication. As a result, thesimulation system has the disadvantages of complex structure,inconvenient maintenance, data delay and limited interface developmentcaused by the relative independence of each simulation software program.Therefore, there is an urgent need for unified representation modelingand simulation research of thermoelectric heterogeneous energy sources.Furthermore, the combined heat and power system includes multiple energylinks such as energy conversion, transmission, dissipation and storage,where due to its own heat capacity and other reasons, a temperature of abuilding heat load changes slowly; and due to a long-distance heattransmission pipeline, dynamic characteristics such as transmissiondelay and heat dissipation in the pipeline are obvious and cannot beignored. However, in a simulation system with “electricity” as a core,device models such as heat and gas are added to power analysis tools,and the models are simple and cannot reflect a dynamic process of athermal system.

SUMMARY

In order to solve the defects of the prior art, the present disclosureprovides a dynamic equivalent circuit of a combined heat and powersystem, and a working method thereof.

In the first aspect, the present disclosure provides a dynamicequivalent circuit of a combined heat and power system.

The dynamic equivalent circuit of a combined heat and power systemincludes:

controlled sources are used to represent a thermoelectric couplingsource; equivalent inductance is used to represent a delay of a heattransmission pipeline; equivalent resistance is used to represent a heatload and a heat loss of the heat transmission pipeline; and equivalentcapacitance is used to represent a heat storage water tank.

In the second aspect, the present disclosure provides a working methodof a dynamic equivalent circuit of a combined heat and power system.

A simulation method of the dynamic equivalent circuit of the combinedheat and power system includes:

controlled sources are used to represent a thermoelectric couplingsource; equivalent inductance is used to represent a delay of a heattransmission pipeline; equivalent resistance is used to represent a heatload and a heat loss of the heat transmission pipeline; and equivalentcapacitance is used to represent a heat storage water tank.

When an electrical load is R_(e), a supply voltage of the thermoelectriccoupling source is U_(e).

The heat flows out of a waste heat recovery system of the thermoelectriccoupling source; and the heat flows through a heating pipeline after atransmission delay time, and a heat loss is generated.

If a first switch and a second switch are all turned on, the heat iscompletely used for heating of a heat load, and the heat completelyflows through the heat load to heat the heat load and then passesthrough a water return pipeline to reach a water return side.

If the first switch and the second switch are turned off at the sametime, part of the heat flows through the heat load to heat the heat loadand then passes through the water return pipeline to reach the waterreturn side, and the other part of the heat flows into the heat storagewater tank and is stored for later use.

Compared with the prior art, the present disclosure has the followingbeneficial effects:

A circuit model is used to uniformly represent two thermoelectricheterogeneous energy sources, and a single power simulation tool may beused to simulate a combined heat and power system, so that thesimulation system has a simple structure and is easy to develop andmaintain, and simulation errors caused by data communications ofmultiple energy software are avoided. By considering the dynamiccharacteristics of a thermal subsystem, the accuracy of the simulationsystem is improved.

An established dynamic equivalent circuit model may be used for analysisof dynamic characteristics of the combined heat and power system, designof control algorithms, and testing of algorithms such as optimizationdesign. In addition, an equivalent circuit may also be simplifiedaccording to the knowledge of electrodynamics, thereby reducing themodel complexity, and protecting the detailed parameter information ofthe system.

The advantages of the additional aspects of the present disclosure willbe partially given in the following description, and parts will becomeobvious from the following description, or be understood through thepractice of the present disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings which constitute a part of the description ofthe present disclosure are intended to provide further understanding ofthe present disclosure. The exemplary examples of the present disclosureand descriptions thereof are intended to explain the present disclosureand do not constitute an inappropriate limitation to the presentdisclosure.

FIG. 1 shows a simulation system of a dynamic equivalent circuit in afirst embodiment.

FIG. 2(a) shows a heat load.

FIG. 2(b) shows an equivalent circuit representation of the heat load.

FIG. 3(a) shows a heat transmission pipeline.

FIG. 3(b) shows an equivalent circuit representation of the heattransmission pipeline.

FIG. 4(a) shows a heat storage water tank.

FIG. 4(b) shows an equivalent circuit representation of the heat storagewater tank.

FIG. 4(c) shows an equivalent circuit representation of the heat storagewater tank.

FIG. 5(a) shows a thermoelectric coupling source device.

FIG. 5(b) shows an equivalent circuit representation of thethermoelectric coupling source device.

FIG. 5(c) shows an equivalent circuit representation of thethermoelectric coupling source device.

FIG. 6 shows a structural diagram of a combined heat and power system.

DETAILED DESCRIPTION OF THE EMBODIMENTS

It should be pointed out that the following detailed description isillustrative and is intended to provide further explanation of thepresent disclosure. Unless otherwise specified, all technical andscientific terms used herein have the same meanings as those generallyunderstood by those of ordinary skill in the art to which the presentdisclosure pertains.

It should be noted that the terms used herein are merely used fordescribing the specific implementations, but are not intended to limitexemplary implementations of the present disclosure. As used herein,unless the context clearly indicates otherwise, the singular forms areintended to include the plural forms as well. Moreover, it should beunderstood that the terms “include”, “have” and any other variants meanto cover a non-exclusive inclusion, for example, a process, method,system, product, or device that includes a list of steps or units is notnecessarily limited to those expressly listed steps or units, but mayinclude other steps or units not expressly listed or inherent to such aprocess, method, system, product, or device.

In addition, the embodiments in the present disclosure and the featuresin the embodiments can be combined with each other in a non-conflictingsituation.

Embodiment 1

This embodiment provides a dynamic equivalent circuit of a combined heatand power system.

As shown in FIG. 1, the dynamic equivalent circuit of the combined heatand power system includes:

controlled sources are used to represent a thermoelectric couplingsource; equivalent inductance is used to represent a delay of a heattransmission pipeline; equivalent resistance is used to represent a heatload and a heat loss of the heat transmission pipeline; and equivalentcapacitance is used to represent a heat storage water tank.

Further, the circuit includes: a first branch and a second branch,

where the first branch includes: an input terminal, a controlled voltagesource U_(e), a resistor R_(e) and an output terminal connected insequence;

the second branch includes: an input terminal, a controlled currentsource I₀ ^(h) and a ground terminal connected in sequence; and

the first branch and the second branch are used to represent thethermoelectric coupling source of the combined heat and power system.

Exemplarily, the thermoelectric coupling source refers to a device thatcan convert a certain energy into electrical energy and thermal energyat the same time, such as a gas turbine that can convert the chemicalenergy of fuel gas into electrical energy and thermal energy at the sametime, and a fuel cell that can convert the chemical energy of hydrogeninto electrical energy and thermal energy at the same time.

Exemplarily, the thermoelectric coupling source: a controlled source ofa circuit element is used to represent a generator set of a combinedheat and power system, such as a gas generator set and a fuel cell.Taking the gas generator set as an object, an energy balance equation isshown in Formula (10), and an outlet temperature U_(h) and a currentI_(e) of cooling water may be derived as Formula (11). FIG. 5(a) shows athermoelectric coupling source device. FIG. 5(b) shows an equivalentcircuit representation of the thermoelectric coupling source device.FIG. 5(c) shows an equivalent circuit representation of thethermoelectric coupling source device.

Further, a mathematical model of the thermoelectric coupling source ofthe combined heat and power system is:

$\begin{matrix}{{{U_{h}I_{h}} = {\frac{\eta_{h}U_{e}I_{e}}{\eta_{e}} + {T_{cooling}I_{h}}}},} & (10)\end{matrix}$

where U_(h) represents an outlet temperature of cooling water; I_(h)represents a heat capacity flow rate of the cooling water; η₃ representsa generating efficiency of a thermoelectric coupling source; U_(e)represents an output voltage of a thermoelectric coupling source; I_(e)represents an output current of the thermoelectric coupling source;T_(cooling) represents an inlet temperature of the cooling water; andη_(h) represents a thermal efficiency of the thermoelectric couplingsource.

Further, the circuit further includes: a third branch and a fourthbranch,

where the third branch is connected in parallel with the second branch;the third branch includes: an input terminal, a virtual resistor R′_(l)and a ground terminal connected in sequence;

the fourth branch includes: an input terminal, an inductor L^(h) _(pd),a resistor R_(pg) ^(h) and an output terminal connected in sequence;

the third branch and the fourth branch are used to represent the heattransmission pipeline of the combined heat and power system; and

the inductor L^(h) _(pd) is used to represent a delay of the heattransmission pipeline.

Exemplarily, a delay phenomenon of heat transmission in the heattransmission pipeline may be described by thermal inductance, which issimilar to a hindering effect of an inductance element on a current in acircuit. Due to model requirements of optimization control of thecombined heat and power system, time constant characteristics of thermalinductance are mainly researched. Combined with a circuit logic, avirtual resistor R′_(l) is designed and connected in parallel with L^(h)_(pd) to form an RL circuit structure, but it has no actual physicalmeaning. A value of R′_(l) needs to be so large that its shunting effectis small enough to be ignored. According to the knowledge ofelectronics, it is believed that after 5^(τ) ^(l) (^(τ) ^(l) is aninductance time constant), an inductance current is stable. Therefore,assuming that a transmission delay time of heat flow is t_(delay), L_(h)is expressed as:

$\begin{matrix}{L_{h} = {{R_{l}^{\prime}\tau_{l}} = {\frac{R_{l}^{\prime}t_{delay}}{5}.}}} & (5)\end{matrix}$

Generally, while there is a delay in pipeline heat transmission, theheat dissipation through a pipeline to an ambient environment is alsoinevitable, that is, there is equivalent resistance.

Further, a mathematical model of the heat loss of the heat transmissionpipeline of the combined heat and power system is:

The resistance R^(h) _(pipe) of the heat transmission pipeline isexpressed as:

$\begin{matrix}{{R_{pipe}^{h} = \frac{( {T_{start} - T_{a}} )( {1 - e^{\frac{{- \lambda}L}{Cp}}} )}{Cp}},} & (6)\end{matrix}$

where T_(start) represents an inlet temperature of the heat transmissionpipeline, T_(a) represents an environmental temperature of the heattransmission pipeline, λ represents a heat dissipation coefficient ofthe pipeline, L represents a length of the pipeline, and Cp represents aheat capacity flow rate of heat flow in the pipeline.

In conclusion, the heat transmission pipeline is shown in FIG. 3(a), andthe equivalent circuit representation of the heat transmission pipelineis shown in FIG. 3(b).

Further, the circuit further includes: a fifth branch.

The fifth branch includes: a resistor R_(load) ^(h), a resistor R_(pr)^(h), a resistor R_(rest) ^(h) and a ground terminal connected insequence, where the resistor R_(load) ^(h) is also connected with anoutput terminal of the resistor R_(pg) ^(h),

where the resistor R_(load) ^(h) represents a heat load of the combinedheat and power system, the resistors R_(pr) ^(h) and R_(rest) ^(h)represent a water return side of the combined heat and power system, andthe resistors R_(pg) ^(h) and R_(pr) ^(h) are used to represent the heatloss of the heat transmission pipeline.

Exemplarily, heat load: all devices having heat dissipation in thecombined heat and power system may be called heat loads, such asbuilding heat loads and heat transmission pipelines with heat losses.Here, the heat load is compared to a resistor, and then an equivalentrepresentation form of dynamic resistance R^(h) is established.

Further, a mathematical model of the heat load of the combined heat andpower system is:

due to the existence of its own heat capacity b, the heat load is heatedto a temperature T_(e) by the heat flow at a heat exchange rate a, and adynamic process of T_(e) temperature rise may be expressed as Formula(1):

$\begin{matrix}{{ T_{e}\overset{▯}{(}t ) = {\frac{a}{b}( {{T_{in}(t)} - {T_{e}(t)}} )}},} & (1)\end{matrix}$

where T_(in)(t) represents an inlet temperature, T_(e)(t)represents aheat load temperature at a time t, and T_(e)

represents a change rate of the heat load temperature at the time t.

At the time t, the heat capacity flow rate of the heat flow is Cp(t), atemperature is T_(in)(t), a heat dissipation rate of the heat load isϕ_(load)(t), and an outlet temperature T_(out)(t) of the heat flowingthrough the heat load is expressed as:

$\begin{matrix}{{T_{out}(t)} = {{T_{in}(t)} - {\frac{{T_{e}\overset{▯}{(}t{) \cdot b}} + {\phi_{load}(t)}}{{Cp}(t)}.}}} & (2)\end{matrix}$

At this time, equivalent resistance R^(h)(t) of the heat load may beexpressed as:

$\begin{matrix}{{R^{h}(t)} = {\frac{{T_{in}(t)} - {T_{out}(t)}}{{Cp}(t)} = {\frac{{ T_{e}\overset{▯}{(}t )b} + \phi_{load}}{\lbrack {{Cp}(t)} \rbrack^{2}}.}}} & (3)\end{matrix}$

Further, a mathematical model of the water return side of the combinedheat and power system is:

$\begin{matrix}{R_{rest}^{h} = {\frac{T_{in}(t)}{{Cp}(t)} - {R^{h}.}}} & (4)\end{matrix}$

In order to solve the contradiction that voltages of parallel circuitsare equal but outlet temperatures of the parallel circuits are notnecessarily equal, a model R^(h) _(rest) on the water return side of theresistor is established, so as to represent the low-grade heat energy ofthe water return side of the resistor.

In conclusion, the heat load is shown in FIG. 2(a), and the equivalentcircuit representation form of the heat load is shown in FIG. 2(b).

Further, the dynamic equivalent circuit of the combined heat and powersystem includes: a sixth branch and a seventh branch,

where the sixth branch includes: a first switch, one end of the firstswitch is connected with an output terminal of the resistor R^(h) _(pg)through a node 2′, and the other end of the first switch is groundedthrough a resistor R′_(c);

the seventh branch includes: a controlled current source I₂ ^(h), oneend of the controlled current source I₂ ^(h) is connected with theoutput terminal, the other end of the controlled current source I₂ ^(h)is grounded through a capacitor C_(s) ^(h), assuming that a connectingpoint between the controlled current source I₂ ^(h) and the outputterminal is a node 2, and a second switch is arranged between the node2′ and the node 2; and

the sixth branch and the seventh branch are used to represent the heatstorage water tank of the combined heat and power system.

Exemplarily, heat storage water tank: since the existence of heatstorage allows a mismatch between a heat demand and heat generation, thecombination of heat storage and combined heat and power systems hasbecome a standard scheme.

Further, a mathematical model of the heat storage water tank of thecombined heat and power system is:

similar to a capacitance element C, a heat capacity C^(h)(t) representsthe heat storage at the time t.

Based on thermoelectric comparison rules, calculation formulas ofC^(h)(t) and total heat storage W_(c) ^(h)(t) at the time t arerespectively:

$\begin{matrix}{{{C^{h}(t)} = \frac{\int\limits_{0}^{t}{{{Cp}_{in}(t)}{dt}}}{T_{\tan k}}},} & (7)\end{matrix}$ $\begin{matrix}{{{W_{c}^{h}(t)} = {{C_{h}(t)}\lbrack {T_{\tan k}(t)} \rbrack}^{2}},} & (8)\end{matrix}$

where Cp_(in)(t) represents a heat capacity flow rate at an inlet of thewater tank, and T_(tank)(t) represents a heat storage water temperatureat the time t. T_(tank)(t) is represented by Formula (9) withoutconsidering the heat dissipation of the water tank:

$\begin{matrix}{{{T_{\tan k}(t)} = \frac{\int\limits_{0}^{t}{{V_{in}(t)}{T_{in}(t)}{dt}}}{\int\limits_{0}^{t}{{V_{in}(t)}{dt}}}},} & (9)\end{matrix}$

where T_(in)(t) and V_(in)(t) respectively represent an inlettemperature and an inlet flow rate of the heat storage water tank at thetime t.

Similar to thermal inductance, C_(h) also needs a virtual resistorR′_(c), which is connected in parallel with a heat load branch, itsvalue is 1/x times the total resistance value of the heat load branch,and its function is to share

$\frac{x}{1 + x}$

times of the total current together with the heat load branch, andassign the current to a current source Ic. Specifically, FIG. 4(a) showsa heat storage water tank; FIG. 4(b) shows an equivalent circuitrepresentation of the heat storage water tank; and FIG. 4(c) shows anequivalent circuit representation of the heat storage water tank.

In the present disclosure, a simulation model of a dynamic equivalentcircuit of a combined heat and power system, including four typicallinks of a thermoelectric coupling source, a heat transmission pipeline,a heat load and heat storage, will be established.

First, according to thermoelectric comparison rules, a heat dissipationprocess of the heat load including a building heat load and a pipelineheat load (pipeline heat energy loss), in the system is compared to aresistance element;

a heat transmission delay is compared to a thermal inductance element;

non-phase change heat storage, which is usually a heat storage watertank, is compared to a heat capacity element; and

a thermoelectric coupling source, which is usually a gas generator set,a fuel cell, etc., is represented in a form of a controlled source.Finally, in combination with a system structure, a model of the dynamicequivalent circuit of the combined heat and power system is constructed,and unified dynamic simulation of the heterogeneous energy flow of thesystem is realized.

In combination with a structural diagram of the combined heat and powersystem in FIG. 6, a complete simulation model of the equivalent circuitof the combined heat and power system, including a thermoelectriccoupling source, a heat transmission pipeline, a heat load and a heatstorage water tank, is shown in FIG. 1, where a controlled source CCCSindicates that when an outlet temperature U^(h) ₀ of cooling water andan output voltage U_(e) of a gas generator set are constant, the a flowrate I^(h) ₀ of the cooling water is controlled by a current I_(e).

A node 0′ is a branch node of an auxiliary resistor ^(R)1 which has nophysical meaning, and since R′_(l) is large enough, I′_(0′) may beapproximately regarded as 0.

L^(h) _(pd) represents a heat transmission delay, R_(pg) ^(h) and R_(pr)^(h) on the water return side respectively represent heat dissipation ofa heat transmission pipeline for heating and a heat transmissionpipeline for water return, R_(rest) ^(h) represents residual resistance,and R_(rest) ^(h) represents lower-grade return water heat energy afterpassing through the heat load. I′₂ is equal to I′_(2′), and I′₂represents an inlet flow rate of a heat storage water tank C_(h) ^(s).The simulation model may be flexibly arranged on power simulationsoftware. A Simscope tool of an MATLAB/Simulink has been used to realizethe simulation of the combined heat and power system, and simulationresults verify that the simulation model is effective.

Embodiment 2

This embodiment provides a simulation method of a dynamic equivalentcircuit of a combined heat and power system.

The simulation method of the dynamic equivalent circuit of the combinedheat and power system includes:

controlled sources are used to represent a thermoelectric couplingsource; equivalent inductance is used to represent a delay of a heattransmission pipeline; equivalent resistance is used to represent a heatload and a heat loss of the heat transmission pipeline; and equivalentcapacitance is used to represent a heat storage water tank.

When an electrical load is R_(e), a supply voltage of a thermoelectriccoupling source is U_(e).

The heat flows out of a waste heat recovery system of the thermoelectriccoupling source; and the heat flows through a heating pipeline after atransmission delay time, and a heat loss is generated.

If a first switch and a second switch are all turned on, the heat iscompletely used for heating of a heat load, and the heat completelyflows through the heat load to heat the heat load and then passesthrough a water return pipeline to reach a water return side.

If the first switch and the second switch are turned off at the sametime, part of the heat flows through the heat load to heat the heat loadand then passes through the water return pipeline to reach the waterreturn side, and the other part of the heat flows into a heat storagewater tank and is stored for later use.

The above description is merely preferred examples of the presentdisclosure and is not intended to limit the present disclosure, andvarious changes and modifications of the present disclosure may be madeby those skilled in the art. Any modifications, equivalentsubstitutions, improvements, and the like made within the spirit andprinciple of the present disclosure shall be included within theprotection scope of the present disclosure.

What is claimed is:
 1. A dynamic equivalent circuit of a combined heatand power system, wherein controlled sources are used to represent athermoelectric coupling source; equivalent inductance is used torepresent a delay of a heat transmission pipeline; equivalent resistanceis used to represent a heat load and a heat loss of the heattransmission pipeline; and equivalent capacitance is used to represent aheat storage water tank.
 2. The dynamic equivalent circuit of a combinedheat and power system according to claim 1, wherein the circuitcomprises a first branch and a second branch, wherein the first branchcomprises: an input terminal, a controlled voltage source U_(e), aresistor R_(e) and an output terminal connected in sequence; the secondbranch comprises: an input terminal, a controlled current source I₀ ^(h)and a ground terminal connected in sequence; and the first branch andthe second branch are used to represent the thermoelectric couplingsource of the combined heat and power system.
 3. The dynamic equivalentcircuit of a combined heat and power system according to claim 1,wherein the circuit further comprises: a third branch and a fourthbranch, wherein the third branch is connected in parallel with thesecond branch; the third branch comprises: an input terminal, a virtualresistor R′_(l) and a ground terminal connected in sequence; the fourthbranch comprises: an input terminal, an inductor L^(h) _(pd), a resistorR_(pg) ^(h) and an output terminal connected in sequence; and the thirdbranch and the fourth branch are used to represent the heat transmissionpipeline of the combined heat and power system.
 4. The dynamicequivalent circuit of a combined heat and power system according toclaim 1, wherein the circuit further comprises: a fifth branch; thefifth branch comprises: a resistor load R_(load) ^(h), a resistor R_(pr)^(h), a resistor R^(h) _(rest) and a ground terminal connected insequence, wherein the resistor load R_(load) ^(h) also connected with anoutput terminal of the resistor R_(pg) ^(h); and the resistor R_(load)^(h) represents a heat load of the combined heat and power system, andthe resistors R_(pr) ^(k) and R_(rest) ^(h) represent a water returnside of the combined heat and power system.
 5. The dynamic equivalentcircuit of a combined heat and power system according to claim 1,further comprising: a sixth branch and a seventh branch, wherein thesixth branch comprises: a first switch, one end of the first switch isconnected with the output terminal of the resistor R_(pg) ^(h) through anode 2′, and the other end of the first switch is grounded through aresistor R′_(c); the seventh branch comprises: a controlled currentsource I₂ ^(h), one end of the controlled current source I₂ ^(h) isconnected with the output terminal, the other end of the controlledcurrent source I₂ ^(h) grounded through a capacitor C_(s) ^(h), assumingthat a connecting point between the controlled current source I₂ ^(h)and the output terminal is a node 2, and a second switch is arrangedbetween the node 2′ and the node 2; and the sixth branch and the seventhbranch are used to represent the heat storage water tank of the combinedheat and power system.
 6. The dynamic equivalent circuit of a combinedheat and power system according to claim 1, wherein a mathematical modelof the thermoelectric coupling source of the combined heat and powersystem is: $\begin{matrix}{{{U_{h}I_{h}} = {\frac{\eta_{h}U_{e}I_{e}}{\eta_{e}} + {T_{cooling}I_{h}}}},} & (10)\end{matrix}$ wherein U_(h) represents an outlet temperature of coolingwater; I_(h) represents a heat capacity flow rate of the cooling water;η_(e) represents a generating efficiency of a thermoelectric couplingsource; U_(e) represents an output voltage of a thermoelectric couplingsource; I_(e) represents an output current of the thermoelectriccoupling source; T_(cooling) represents an inlet temperature of thecooling water; and η_(h) represents a thermal efficiency of thethermoelectric coupling source.
 7. The dynamic equivalent circuit of acombined heat and power system according to claim 1, wherein amathematical model of the heat loss of the heat transmission pipeline ofthe combined heat and power system is: $\begin{matrix}{{R_{pipe}^{h} = \frac{( {T_{start} - T_{a}} )( {1 - e^{\frac{- {\lambda L}}{Cp}}} )}{Cp}},} & (6)\end{matrix}$ wherein R^(h) _(pipe) represents resistance of the heattransmission pipeline, T_(start) represents an inlet temperature of theheat transmission pipeline, T_(a) represents an environmentaltemperature of the heat transmission pipeline, λ represents a heatdissipation coefficient of the pipeline, L represents a length of thepipeline, and Cp represents a heat capacity flow rate of heat flow. 8.The dynamic equivalent circuit of a combined heat and power systemaccording to claim 1, wherein a mathematical model of the heat load ofthe combined heat and power system is: due to the existence of its ownheat capacity b, the heat load is heated to a temperature T_(e) by theheat flow at a heat exchange rate a, and a dynamic process of T_(e)temperature rise is expressed as: $\begin{matrix}{{ T_{e}\overset{▯}{(}t ) = {\frac{a}{b}( {{T_{in}(t)} - {T_{e}(t)}} )}},} & (1)\end{matrix}$ wherein T_(in)(t) represents an inlet temperature,T_(e)(t) represents a heat load temperature at a time t, and T_(e)

represents a change rate of the heat load temperature at the time t;when the heat capacity flow rate of the heat flow is Cp(t) and a heatdissipation rate of the heat load is ϕ_(load), an outlet temperatureT_(out)(t) of the heat flowing through the heat load is expressed as:$\begin{matrix}{{{T_{out}(t)} = {{T_{in}(t)} - \frac{{T_{e}\overset{▯}{(}t{) \cdot b}} + \phi_{load}}{{Cp}(t)}}};} & (2)\end{matrix}$ then, equivalent resistance R^(h)(t) of the heat load isexpressed as: $\begin{matrix}{{{R^{h}(t)} = {\frac{{T_{in}(t)} - {T_{out}(t)}}{{Cp}(t)} = \frac{{ T_{e}\overset{▯}{(}t )b} + \phi_{load}}{\lbrack {{Cp}(t)} \rbrack^{2}}}};} & (3)\end{matrix}$ and a mathematical model of the water return side of thecombined heat and power system is: $\begin{matrix}{R_{rest}^{h} = {\frac{T_{in}(t)}{{Cp}(t)} - {R^{h}.}}} & (4)\end{matrix}$
 9. The dynamic equivalent circuit of a combined heat andpower system according to claim 1, wherein a mathematical model of theheat storage water tank of the combined heat and power system is: basedon thermoelectric comparison rules, calculation formulas of heat storageC^(h)(t) and total heat storage W_(c) ^(h) are respectively:$\begin{matrix}{{{C^{h}(t)} = \frac{\int\limits_{0}^{t}{{{Cp}_{in}(t)}{dt}}}{T_{\tan k}}},} & (7)\end{matrix}$ $\begin{matrix}{{W_{c}^{h} = {C_{h}T_{\tan k}^{2}}},} & (8)\end{matrix}$ wherein Cp_(in)(t) represents a heat capacity flow rate atan inlet of the water tank, and T_(tank)(t) represents a heat storagewater temperature and is represented by Formula (9) without consideringthe heat dissipation of the water tank: $\begin{matrix}{{{T_{\tan k}(t)} = \frac{\int\limits_{0}^{t}{{V_{in}(t)}{T_{in}(t)}{dt}}}{\int\limits_{0}^{t}{{V_{in}(t)}{dt}}}},} & (9)\end{matrix}$ wherein T_(in)(t) represents an inlet temperature of theheat storage water tank at the time t, and V_(in)(t) represents an inletflow rate of the heat storage water tank at the time t.
 10. A simulationmethod of a dynamic equivalent circuit of a combined heat and powersystem, comprising: when an electrical load is R_(e), a supply voltageof a thermoelectric coupling source is U_(e); the heat flows out of awaste heat recovery system of the thermoelectric coupling source; theheat flows through a heating pipeline after a transmission delay time,and a heat loss is generated; if a first switch and a second switch areall turned on, the heat is completely used for heating of a heat load,and the heat completely flows through the heat load to heat the heatload and then passes through a water return pipeline to reach a waterreturn side; and if the first switch and the second switch are turnedoff at the same time, part of the heat flows through the heat load toheat the heat load and then passes through the water return pipeline toreach the water return side, and the other part of the heat flows into aheat storage water tank and is stored for later use.